A database query returns several rows which I loop through as follows:

    foreach ($query->result() as $row) {

        $data[$row->post_id]['post_id']         = $row->post_id;
        $data[$row->post_id]['post_type']       = $row->post_type;
        $data[$row->post_id]['post_text']       = $row->post_text;
    }

If I json_encode the resulting array ($a['stream']) I get

{
    "stream": {
        "1029": {
            "post_id": "1029",
            "post_type": "1",
            "post_text": "bla1",
        },
        "1029": {
            "post_id": "1030",
            "post_type": "3",
            "post_text": "bla2",
        },
        "1029": {
            "post_id": "1031",
            "post_type": "2",
            "post_text": "bla3",            
        }
    }
}

But the json should actually look like this:

{
    "stream": {
        "posts": [{
            "post_id": "1029",
            "post_type": "1",
            "post_text": "bla1",
        },
        {
            "post_id": "1030",
            "post_type": "3",
            "post_text": "bla2",
        },
        {
            "post_id": "1031",
            "post_type": "2",
            "post_text": "bla3",            
        }]
    }
}

How should I build my array to get this json right?